"It was extremely lucky that no one appeared to be seriously injured, as there was debris all around us . . .

"Just why the Toia tug master was so close to the Queen Elizabeth [is unclear]. I can only assume he wanted to give the passengers a thrill and we certainly got that and more."

A Maritime NZ spokesman said "preliminary inquiries" were under way, which should take about two days.

There was slight damage to the cruise ship's platform, "but nothing to impede or significantly delay departure that evening".

It was unusual for the tug to be so close to the cruise ship, he said.

Cruise New Zealand chairman Craig Harris, agent for the Queen Elizabeth, said under usual circumstances in a collision ship owner Cunard would "note protest" with the port about the incident while awaiting an investigation.

There were hundreds of similar incidents each year, he said. "This was unusual because the ship was sitting alongside [the wharf] and the bloody thing hit it."